Even before his comments over the past several days, the confusion surrounding how ballots should be cast and counted had reached a level rarely before seen.
In Wisconsin and Pennsylvania, two states pivotal to the outcome of the presidential race between Mr. Trump and Joseph R. Biden Jr., the Democratic nominee, there are legal fights underway that could affect when voters have to mail in their ballots. In Pennsylvania and Ohio, there are lawsuits about where voters might be able to drop off their ballots.
In those states and others, the very means by which the election will be conducted is still being hashed out through legislation, executive actions and consent decrees, as well as litigation.
In Michigan, legislation is pending concerning whether voters will have the ability to fix any problems with their mail-in ballots. In North Carolina, elections officials signed an agreement to extend the deadline for receiving mail ballots by six days, and Republicans immediately pledged to try to overturn it.
The problem has been exacerbated by the options that states have sought to provide to make voting safer and easier amid the pandemic, changes that have often been met with a flood of lawsuits.
“A whole bunch of Americans are going to have a different process than they may be used to,” said Justin Levitt, a professor at Loyola Law School who oversaw voting rights in the Obama administration as a deputy assistant attorney general. Mr. Levitt has been tracking pandemic-related election law cases across the country, and he said that “any change is inevitably going to lead to disruption.”